Gardaí in Dublin are questioning four men in connection with the murder of 21-year-old Darren Guerrine last month.
The four were all detained yesterday morning, but news of the arrests only emerged today.
Reports this morning say the men are aged between 16 and 19 and are from the Bluebell and Inchicore areas.
Mr Guerrine was shot dead on the banks of the Grand Canal in Bluebell on February 18.